1. Field of the Invention
The present invention relates to a device and method for stacking units for a secondary battery, and more particularly, to a device and method for stacking units for a secondary battery which conveniently stacks a plurality of radical units having different sizes by using a stack jig.
2. Description of the Related Art
Secondary batteries may be variously classified according to structures of electrode assemblies. For example, secondary batteries may be classified into stack-type batteries, winding-type (jell-roll-type) batteries, and stack/folding-type batteries. An electrode assembly of stack-type batteries is formed by cutting cathodes, separators, and anodes to a predetermined size and then stacking the cathodes, the separators, and the anodes. The separators are disposed between the cathodes and the anodes, respectively. An electrode assembly of winding-type batteries is formed by forming a cathode, a separator, an anode, and a separator into sheet shapes, then, sequentially stacking the cathode, the separator, the anode, and the separator, and then, winding the cathode, the separator, the anode, and the separator. An electrode assembly of stack/folding-type batteries is formed by forming full-cells or bi-cells and then winding the full-cells or the bi-cells with a separator sheet. The full-cells or the bi-cells may be formed by cutting a cathode, a separator, and an anode to a predetermined size and then sequentially stacking the cathode, the separator, and the anode (each of the full-cells or the bi-cells includes one or more cathodes, one or more separators, and one or more anodes).
A detailed description of an electrode assembly having a stack-type structure is disclosed in Korean Patent Registration No. 10-1163053, which was filed by the applicant of the present invention.
Recent electrode assemblies have a stacked structure formed in a stepped manner to be installed in a miniaturized product.
In particular, referring to FIG. 1, a related art stack-type electrode assembly 20 having a stacked structure formed in a stepped manner includes: one or more first radical units 21 having a first size; one or more second radical units 22 having a second size greater than the first size, wherein the first radical units 21 are stacked on the second radical units 22; and one or more third radical units 23 having a third size greater than the second size, wherein the second radical units 22 are stacked on the third radical units 23.
However, when the first to third radical units 21, 22, and 23 of the stack-type electrode assembly 20 are stacked, it is difficult to precisely position the first to third radical units 21, 22, and 23. Furthermore, the first and second radical units 21 and 22 may be moved to cause a defect. To address these problems, stacking positions of the first to third radical units 21, 22, and 23 are adjusted through a separate process.